You do have to keep mileage records for the IRS tax prep and differentiate between
business,
personal,
charity and
moving miles.
You can take a business vehicle tax deduction with receipts for all expenses or mileage deduction.

For 2009 business miles driven at $0.55 per mile (55 cents per mile)

For 2009 charity miles driven are @ $0.14 per mile.

For 2009 moving and medical miles driven are @ $0.24 per mile.

The charity, medical and moving mileage deductions are not as much of an advantage.
You can do straight deductions of all expenses repairs fuel etc. or take the mileage deduction. So let's focus on business here a bit.

The business miles are often the best deduction and even though the
price
of gas is coming down as of fall of 2008. You never know what gas prices will do.

If you have a business that logs a lot of highway
miles
like I do at 55 cents per mile it still should be a better method for
2009. Best keep track by both methods so that when tax time comes
you can
do the math and decide which is the better.

Keep a log book to track the odometer readings each day.
I was told how mileage was re-created for one day when they forgot to log the
difference between personal miles and business. They went to a website
that offers online maps and driving directions and mapped out the trip.

You will find software programs that are very helpful for tax prep and many
people use them.

I like to do all of the preliminary record keeping work and
trust my accountant for the details.

Some people think that they don't need to use an accountant because the
electronic filing and tax prep software is so easy to use.

I'll have to look into it because it's surely worth the effort to learn about the
ease of use of the software
and decide if you want to
save the cost of the
accountant.

You also have the option of deducting using the percentage method whereby
you have to save all receipts for parking fees, gas, registration, repairs etc.
If you had a catastrophic year, repair wise, or had to park in a pay garage
everyday
that might warrant keeping all records and possibly using the
percentage
method.

Medical and moving allows a $0.19 per mile deduction. For some it is negligeble.

Some people have to travel for dialysis or chemotherapy on a
regular basis. For them it is vital that they save the money using the
deduction.

The charity deduction @ $0.14 could be an issue if you did it on a regular basis but again
you have to check the numbers.

The above info can be a make it or break it sitution.

If you are self-employed and
just starting out in business for yourself you have to think about this right
away so that your records will be
accurate.
The mileage deduction amounts change every year so be sure to come to visit this site before you start every new year just to know where you will stand deduction wise.

Notes: This is often referred to as the federal mileage rate., and answers questions about federal mileage reimbursement.
Federal mileage allowance is the topic. Someone spelled it milage. You ask, what is the federal irs mileage rate standard or IRS mileage rate reimbursement? Read the above.
You do have to keep an irs mileage log.